Have a 10-year old Honda that starts and runs great. I made the mistake of turning the mower on it's side to look at the blades to see if they need to be sharpened....and left it on it's side with the air filter down. When I came back, all the oil had leaked out. After cleaning things up and removing the air filter to get all the oil out, I'm not able to start the mower. I let it sit overnight and have since changed the spark plug in case it got fouled. No luck.

What do I need to do get the mower started again? Thanks!